Support frame for an embolic protection device

ABSTRACT

A support  103  for an embolic protection device comprises round wires  116  which may form one or more support hoops for a filter body. The circumferential hoop formed by the wires  116  ensures that in the expanded position, the filter body  102  will be supported by the support frame  103  in circumferential apposition with the interior wall of the vasculature. The wires  116  may have a strain distributing linkage element in the form of a loop  120 . The loop  120  acts as a diameter or circumference adjuster allowing an embolic protection device to adapt to different Bessel contours and sizes whilst maintaining apposition with the vessel wall. The strain relieving geometry of the loops enhances the compliance of the bend points without creating a weakened hinge point, thus ensuring that there is no discontinuity in the circumferential seal against the vessel wall.

This application is a continuation of U.S. application Ser. No.11/332,485 filed Jan. 17, 2006, which is a continuation of U.S.application Ser. No. 10/325,954, filed Dec. 23, 2002, now U.S. Pat. No.7,037,320, and claims benefit under 35 U.S.C. § 119 to U.S. ProvisionalApplication 60/341,836 filed Dec. 21, 2001, U.S. Provisional ApplicationNo. 60/341,805 filed Dec. 21, 2001, U.S. Provisional Application No.60/373,640 filed Apr. 19, 2002, U.S. Provisional Application No.60/373,641 filed Apr. 19, 2002 and U.S. Provisional Application No.60/377,248 filed May 3, 2002, all of the disclosures of which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an embolic protection device.

In particular, it relates to an embolic protection device of the typecomprising a collapsible filter body to capture embolic material, and asupport to maintain the filter body in an expanded position when theembolic protection device is deployed in a vasculature.

2. Description of the Related Art

Embolic protection devices of this general type are known.

However, there exist a number of problems with some of the knowndevices. In particular, upon collapse of the filter support, prior todelivery of the embolic protection device into and/or retrieval from avasculature, large, localized stresses may be induced in the support.Solutions to this problem heretofore may result in features whichinhibit the optimum performance of the device. In some systems flowpaths for the blood can develop between the filter body and the interiorwall of the vasculature. In general conventional devices are not highlytrackable because of their length in the wrapped delivery configuration.

There is therefore a need for an embolic protection device whichovercomes at least some of the disadvantages that exist with some of theknown devices.

SUMMARY OF THE INVENTION

According to the invention there is provided an embolic protectiondevice comprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a number of segments at least some        of which are interconnected by a strain distributing linking        element.

In one embodiment at least some of the segments are of wire.

The linking element may be of wire. The linking element may be of thesame wire as that of the support segments.

In one embodiment the linking element extends normally of adjacentsegments. The linking element may extend longitudinally of the axis ofthe filter and/or the linking element extends radially inwardly of theadjacent segments.

In a preferred embodiment the linking element comprises a loop. The loopmay be of generally omega shape.

In one embodiment at least portion of the linking element is radiopaque.Alternatively or additionally at least portion of at least some of thesupport segments are radiopaque.

In one embodiment the linking element is of multifilament construction.Alternatively or additionally at least one of the support segments is ofmultifilament construction.

In one embodiment the support frame is defined by at least two wiresegments terminating distally, the distal terminations of adjacentsegments being fixed relative to one another and extending generallyparallel.

The support frame may be defined by at least two wire segmentsterminating proximally, the proximal terminations of adjacent segmentsbeing fixed relative to one another and extending generally parallel.

In one embodiment the support frame comprises a support arm for one endof the filter body which extends towards on opposite end of the filterbody in the deployed configuration.

In one embodiment the device comprises a carrier extendinglongitudinally of the frame. The carrier may be a tubular member, sleeveor sleeves or may comprise a guidewire.

A flexible tether may extend between the carrier and the support frame.

In one embodiment the support frame comprises a support loop or hoop.

In another aspect the invention provides an embolic protection devicecomprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filler body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a support frame having at least        two longitudinally spaced-apart segments which are        interconnected by at least one flexible linking element.

The support frame segments may be of wire.

In a further aspect the invention provides an embolic protection devicecomprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a support frame defined by at        least two wire segments having terminations, the terminations of        adjacent segments being fixed relative to one another and        extending generally parallel.

The wire segments may terminate distally, the distal terminations ofadjacent segments being fixed relative to one another and extendinggenerally parallel. Alternatively or additionally the wire segmentsterminate proximally, the proximal terminations of adjacent segmentsbeing fixed relative to one another and extending generally parallel.

The terminations may extend axially in relation to the filter. Thedistal terminations may be free to move axially. Alternatively oradditionally the proximal terminations are free to move axially.

In one embodiment the proximal terminations of adjacent wire segmentsare configured to meet in a loop formation. The distal terminations ofadjacent wire segments may be configured to meet in a loop formation.

In one embodiment the wire segments are of substantially the samelength.

The wire segments may be fixed relative to one another by soldering, orwelding, or bonding the wire segments to one another. Alternatively oradditionally the device comprises a clamp around the wire segments tofix the wire segments relative to one another. The clamp may comprise atubular sleeve. The clamp may comprise a clamp wire wound around thewire segments. The clamp may be at least partially of radiopaquematerial.

In one embodiment the wire segments are provided by a single wire bentback on itself.

Terminations may be located on an outer circumference of the filterframe. Alternatively or additionally terminations are located on an axisof the filter.

One of the proximal or distal terminations may be located on an outercircumference of the filter frame and the other of the proximal ordistal terminations located on an axis of the filter.

In one embodiment each wire element has a circumferentially extendingportion, and together the circumferentially extending portions of thewire elements define a cell which forms a substantially complete loop.

The wire elements may together define a number of cells axiallyspaced-apart. The support frame may have a connector between a firstcell and a second cell.

The wire element may extend in an irregular path such as in asubstantially wave-like pattern.

In one embodiment the wire element extends in an arcuate path.

In one embodiment the filter support comprises at least one support legextending radially inwardly from the support frame, the leg beingdefined by at least one wire. The cross-sectional area of the supportleg may decrease radially inwardly.

In one embodiment at least part of the support leg is integral with atleast part of the support frame. The support leg may be provided as anextension of one wire element and/or the support leg is provided as anextension of two or more adjacent wire elements.

In one embodiment the support leg extends at least partially distallyinwardly from the support frame.

The wire element may have a round cross-section.

Alternatively, the wire element has an elongate cross-section with along dimension and a short dimension. The short dimension of the wireelement cross-section may be aligned substantially along the radialdirection of the filter support. The wire element may be rectangular incross-section.

In one embodiment the filter body comprises a flap wrappable around awire element of the filter support to fix the filter body to the filtersupport.

In another aspect the invention provides a method of collapsing anembolic protection device for delivery and/or retrieval of the devicethrough a vascular system, the method comprising the steps of:

-   -   providing an embolic protection device comprising a collapsible        filter body and a filter support for the filter body; and    -   collapsing the filter support to a low-profile configuration        with an associated torqueing of at least part of the filter        support upon elongation of the filter support.

In another aspect the invention, an embolic protection device,comprises:

-   -   a collapsible filter element for delivery through a vascular        system of a patient; the filter element comprising a collapsible        filter body and a filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position; the filter support comprising a support        frame, a carrier, and    -   a flexible tether extending between the carrier and the support        frame.

In one embodiment the carrier extends longitudinally of the frame. Thecarrier may be a tubular member or sleeve(s). Alternatively the carrieris a guidewire. The filter support may comprise a number of segments, atleast some of which are interconnected by a strain distributing element.

The filter support may comprise a loop.

In one embodiment at least some of the segments are of wire. The linkingelement may be of wire. The linking element may be of the same wire asthat of the support segments. The linking element may extend normally ofadjacent segments, for example longitudinally of the axis of the filterand/or radially inwardly of the adjacent segments.

In one embodiment the linking element comprises a loop which may be ofgenerally omega shape.

At least portion of the linking element may be radiopaque. At least someof the support segments may be radiopaque.

In one embodiment the linking element is of multifilament construction.

In another embodiment at least one of the support segments is ofmultifilament construction.

In one embodiment the support frame is defined by at least two wiresegments having terminations, the terminations of adjacent segmentsbeing fixed relative to one another and extending generally parallel.The support frame may be defined by at least two wire segmentsterminating distally, the distal terminations of adjacent segments beingfixed relative to one another and extending generally parallel. Thesupport frame may be defined by at least two wire segments terminatingproximally. the proximal terminations of adjacent segments being fixedrelative to one another and extending generally parallel.

In one embodiment the support frame comprises a support arm for one endof the filler body which extends towards on opposite end of the filterbody in the deployed configuration.

In one embodiment the device comprises a carrier extendinglongitudinally of the frame. A flexible tether may extend between thecarrier and the support frame.

In one embodiment the support frame comprises a support loop.

In another aspect the invention provides an embolic protection devicecomprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end. the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a support frame,    -   a support arm for one end of the filter body which extends        towards an opposite end of the filter body in the deployed        configuration.

The support arm may be a proximal support arm that extends distally inthe deployed configuration. Alternatively or additionally the supportarm is a distal support arm that extends proximally in the deployedconfiguration.

In a further aspect the invention provides an embolic protection devicecomprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a generally tubular support frame        defined by at least one wire.

The at least one wire of the tubular support frame becomes torquedduring collapse of the filter support. This torque induced upon collapseis evenly distributed along the wire without resulting in stressconcentrations on the filter support. ‘thus, the wires may be of a smallcross-sectional area which advantageously collapse down to a very lowprofile.

In addition, small wires enable greater flexibility for the filterelement, which allow for ease of advancement through the vascularsystem.

The frame may comprise a number of cells, at least one of the cellsdefining a segment of a tube. Each cell may define a segment of a tube.

In one embodiment at least portion of an element of one cell isconnected to an element of another cell. The connection means may beprovided by an extension wire between the cells. At least portion of anelement of one cell may be directly fixed to an element of another cell.

The or each cell may be defined by two wire elements. The two wireelements may be of substantially the same length. The or each wireelement may have a proximal termination and a distal termination, andthe proximal terminations of adjacent wire elements are fixed relativeto one another, and/or the distal terminations of adjacent wire elementsare fixed relative to one another.

The terminations of adjacent wire elements may extend generally axiallyand parallel. The proximal terminations may be circumferentially alignedwith the distal terminations. Alternatively the proximal terminationsare circumferentially offset from the distal terminations.

In one embodiment each wire element has an axially extending portion anda circumferentially extending portion.

In one embodiment at least one wire element has an S-shaped portion fordistributed filter body support.

The wire elements may be provided by a single wire bent back on itself.The single wire may have a strain relief means at the bend in the wire.The wire may be treated to minimize stress at the bend in the wire.

In one embodiment the filter support comprises at least one support legextending radially inwardly from the tubular support frame, the legbeing defined by at least one wire. At least part of the support leg isintegral with at least part of the tubular support frame. The supportleg may extend distally inwardly from the support frame.

According to a further aspect of the invention, there is provided anembolic protection device comprising:

-   -   a collapsible filter element for delivery through a vascular        system of a patient;    -   the filter element comprising a collapsible filter body and a        filter support for the filter body;    -   the filter body having an inlet end and an outlet end, the inlet        end of the filter body having one or more inlet openings sized        to allow blood and embolic material enter the filter body, the        outlet end of the filter body having a plurality of outlet        openings sized to allow through passage of blood but to retain        undesired embolic material within the filter body;    -   the filter support being movable between a collapsed position        for movement through the vascular system, and an extended        outwardly projecting position to support the filter body in an        expanded position;    -   the filter support comprising a support frame defined by at        least two wire elements, each wire element having a proximal        termination and a distal termination, the terminations of        adjacent elements extending generally axially and parallel.

According to the invention, there is provided a medical device having acollapsed configuration for transport through a body passageway, and anexpanded configuration for deployment in a body;

the medical device comprising a support movable from the collapsedconfiguration to the expanded configuration to support the medicaldevice in the expanded configuration;

the support comprising a radiopaque core.

The second moment of area of the radiopaque material is proportional tothe fourth power of its diameter. Therefore because the radiopaquematerial is provided as the core of the support, this greatly reducesthe diameter and thus the second moment of area of the radiopaquematerial. Correspondingly the forces required to facilitate deploymentof the medical device are also greatly reduced.

In this manner the invention minimizes the dampening effect of theradiopaque material on the medical device.

By locating the radiopaque material as the core of the support, thisalso results in a low-profile medical device.

In one embodiment of the invention the core is located substantiallyalong the neutral axis of bending of the support.

Preferably the support comprises at least one support element. Thesupport element may be of a superelastic material. Ideally theradiopaque core is provided as a core embedded within at least onesupport element. In one case the radiopaque core is in powder form. Inanother case the radiopaque core is in liquid form.

In a preferred embodiment the radiopaque core comprises a radiopaqueelement amongst a plurality of support elements. The element maycomprise a wire. Ideally the elements are wound together.

The radiopaque core may be of mercury, or gold, or platinum.

In another aspect. the invention provides a medical device having acollapsed configuration for transport through a body passageway, and anexpanded configuration for deployment in a body;

the medical device comprising a support movable from the collapsedconfiguration to the expanded configuration to support the medicaldevice in the expanded configuration;

the support comprising a reservoir enclosing a fluid, the fluid beingexpandable upon an increase in temperature to bias the support to theexpanded configuration.

According to a further aspect of the invention, there is provided amedical device having a collapsed configuration for transport through abody passageway. and an expanded configuration for deployment in a body;

the medical device comprising a support movable from the collapsedconfiguration to the expanded configuration to support the medicaldevice in the expanded configuration;

the support comprising a reservoir enclosing a fluid, the fluid beingpressurized to bias the support to the expanded configuration uponrelease of a constraint.

In one case the reservoir comprises an enclosed tube. The tube mayextend at least partially circumferentially around the device. Ideallythe ends of the tube meet to form an enclosed loop.

The fluid may be of a radiopaque material. Preferably the fluid isliquid mercury.

In a preferred embodiment of the invention the device is anintravascular medical device for transport through a vasculature anddeployment in a vasculature. Most preferably the device is an embolicprotection filter. Ideally the filter comprises a filter body supportedby the support, the filter body having an inlet end and an outlet end,the inlet end of the filter body having one or more inlet openings sizedto allow blood and embolic material enter the filter body, and theoutlet end of the filter body having a plurality of outlet openingssized to allow through passage of blood but to retain undesired embolicmaterial within the filter body.

According to the invention, there is provided a medical device having acollapsed configuration for transport through a body passageway, and anexpanded configuration for deployment in a body;

the medical device comprising a support movable from the collapsedconfiguration to the expanded configuration to support the medicaldevice in the expanded configuration;

at least part of the support being of a multifilament wire construction.

In the multifilament wire construction of the invention, each filamentbends independently of the other filaments. Correspondingly, the overallforce required to bend the support is a summation of the forces requiredto bend each filament. Because the force required to bend a wire isproportional to the fourth power of the diameter of the wire, theoverall force required to bend the multifilament support is much lessthan the force which would be required to bend a single wire with thesame overall diameter as the multifilament support.

In this manner, the medical device of the invention achieves enhancedtrackability during transport through even tortuous body passageways,while ensuring the medical device is moved by the support from thecollapsed configuration to the expanded configuration upon deployment inthe body.

The multifilament wire construction also provides the medical devicewith greater deformability in the expanded configuration. This enablesthe medical device to adapt to the particular characteristics of thebody passageway in which it is deployed.

In one embodiment of the invention at least one filament is wound aroundat least one other filament. By winding the filament, the bending stressinduced in the filament is reduced. Preferably at least some of thefilaments arc braided together.

In a particularly preferred embodiment at least one filament is of aradiopaque material. The radiopaque nature of the filament providesvisualization of the medical device during transport through anddeployment in a body. The radiopaque filament is ideally locatedsubstantially along the neutral axis of bending of the support.

In another case at least one filament may comprise a radiopaque coreembedded within the filament.

In a further embodiment of the invention the support comprises a jacketaround the filaments. The jacket helps to maintain the structure of themultifilament wire construction intact and ensure the filaments move ina coordinated manner. Preferably the filaments are embedded within thejacket. Ideally the jacket is at least partially of a radiopaquematerial. The jacket may be at least partially of a polymeric material.

Desirably the support is of the multifilament wire construction at apoint of high curvature in the expanded support.

The device is preferably an intravascular medical device for transportthrough a vasculature and deployment in a vasculature. Ideally thedevice is an embolic protection filter. Most preferably the filter hasan inlet end and an outlet end, the inlet end having one or more inletopenings sized to allow blood and embolic material enter the filter, andthe outlet end having a plurality of outlet openings sized to allowthrough passage of blood but to retain undesired embolic material withinthe filter.

In a preferred case the filter comprises a filter body supported by thesupport, and the inlet openings and the outlet openings are provided inthe filter body to retain undesired embolic material within the filterbody. The filaments may define a mesh. Ideally the inlet openings andthe outlet openings are provided by openings through the mesh.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only.with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an embolic protection device accordingto the invention;

FIGS. 2 and 3 are perspective views of a filter support of the embolicprotection device of FIG. 1;

FIG. 4 is an end view of the filter support of FIGS. 2 and 3;

FIGS. 5 to 7 are perspective views illustrating collapse of the filtersupport of FIGS. 1 to 4;

FIG. 8A is an enlarged view of part of the filter support of FIG. 5;

FIG. 8B is an enlarged view of part of the filter support of FIG. 6;

FIG. 9 is a perspective view of the filter support of FIGS. 1 to 7;

FIGS. 10 to 20 are views of various alternative strain distributinglinkage elements;

FIG. 21 is a perspective view of another filter support;

FIG. 22 is an end view of the filter support of FIG. 21;

FIGS. 23 to 25 are perspective views of part of other filter supports:

FIG. 26 is a perspective view of a further filter support;

FIG. 27 is a perspective view of part of the filter support of FIG. 26in use;

FIG. 28 is a view along line A-A in FIG. 27;

FIGS. 29 and 30 are enlarged perspective views of part of other filtersupports;

FIG. 31 is a perspective view of another device of invention;

FIG. 32 is a perspective view of the device of FIG. 31, in use;

FIG. 33 is a cross sectional view on the line A-A in FIG. 31;

FIG. 34 is a cross sectional view on the line B-B in FIG. 31;

FIG. 35 is a cross sectional view similar to FIG. 34 of an alternativeembolic protection device.

FIGS. 36 and 37 are perspective views of other embolic protectiondevices according to the invention;

FIG. 38 is a perspective view of another embolic protection device;

FIG. 39 is a perspective view of an embolic protection device;

FIG. 40 is a perspective view of a further embolic protection device;

FIG. 41 is a perspective view of another embolic protection device;

FIG. 42 is a longitudinal cross-sectional view of the device of FIG. 41;

FIG. 43 is a cross-sectional view on the line A-A in FIG. 41;

FIG. 44 is a perspective view of another embolic protection device;

FIG. 45 is a cross-sectional view of the device of FIG. 44;

FIG. 46 is a perspective view of a support frame of the invention;

FIG. 47 is an end view in the direction of the arrow A in FIG. 46;

FIGS. 48 to 51 are views similar to FIGS. 46 and 47 of further supportframes;

FIGS. 52 to 62 are various views of linkage elements renderedradiopaque;

FIG. 63 is a perspective view of a portion of a frame element or alinkage element;

FIG. 64 is a perspective view of the element of FIG. 63, in use;

FIGS. 65 and 66 are perspective views of alternative frame elements orlinkage elements;

FIG. 67 is a perspective view of a portion of another frame element orlinkage element of the invention;

FIG. 68 is a perspective view of the element of FIG. 67, in use;

FIGS. 69 to 77 are perspective views of portions of frame elements orlinkage elements;

FIGS. 78 to 81 are perspective views of portions of other frame elementsor linkage elements;

FIG. 82 is a perspective view of a support frame of the invention;

FIG. 83 is a perspective view of another support frame of the invention;

FIGS. 84 to 86 are perspective views of portions of other frame elementsor linkage elements;

FIGS. 87 to 99 are perspective views of various support frames of theinvention. most of which include tether elements;

FIGS. 100A to 100D are perspective views illustrating one attachment ofa tether to a support frame;

FIG. 101 is a perspective view of another support frame includingtethers;

FIG. 102 is a perspective view of portion of a further support frame;

FIG. 103 is a perspective view of another embolic protection device ofthe invention;

FIG. 104 is a perspective view of another support frame;

FIG. 105 is a perspective view of a further support frame;

FIG. 106 is a perspective view of another embolic protection device;

FIG. 107 is a perspective view of another support;

FIG. 108 is a perspective view of a further support

FIG. 109 is a perspective view illustrating the wrapping down of theframe of FIG. 108;

FIGS. 110 and 111 are views similar to FIGS. 108 and 109 of anothersupport frame;

FIGS. 112 to 115 are perspective views illustrating termination details;

FIG. 116 is a perspective view of another support frame;

FIG. 117 is a perspective view of another embolic protection device;

FIG. 118 is a perspective view of a further embolic protection device;

FIGS. 119 to 125 are perspective views of various terminations;

FIG. 126 is a perspective view of another embolic protection device ofthe invention;

FIG. 127 is a perspective view of the support frame of FIG. 126;

FIGS. 128 and 129 are perspective views illustrating the wrap-down ofthe frame of FIG. 127;

FIG. 130 is a perspective view of another embolic protection device;

FIG. 131 is a perspective view of a further embolic protection device;

FIGS. 132 to 134 illustrate steps in the method for forming embolicprotection devices of FIG. 131;

FIG. 135 is a perspective view of another embolic protection device;

FIG. 136 is a perspective view of an embolic protection device;

FIG. 137 is a perspective view of another embolic protection device;

FIG. 138 is a perspective view of a further embolic protection device;

FIG. 139 is a perspective view of another embolic protection device;

FIG. 140 is a perspective view of another support frame of theinvention;

FIG. 141 is a perspective view of another embolic protection device;

FIG. 142 is a perspective view of a support frame of the device of FIG.141;

FIG. 142A is a detail view of portion of the support frame of FIG. 142B;

FIG. 142B is a plan view of an offset variant of the support frame ofFIG. 142;

FIG. 143 is a perspective view of an alternative support frame;

FIG. 144 is a perspective view of an embolic protection device with asingle loop support frame;

FIG. 145 is a perspective view of another embolic protection device;

FIGS. 146 to 148 are perspective views of support frames of theinvention;

FIG. 149 is a perspective view of another support frame;

FIG. 150 is a view of a detail of the frame of FIG. 149;

FIG. 151 is a view of an alternative detail of the frame of FIG. 149;

FIG. 152 and FIG. 153 are views of the frame of FIG. 149 being wrappeddown;

FIG. 154 is a perspective view of another embolic protection device;

FIG. 155 is a perspective view of a support frame of the device of FIG.154;

FIG. 166 is a perspective view of the filter support of FIG. 164;

FIG. 167 is a schematic side view illustrating collapse of the embolicprotection device of FIG. 162;

FIG. 168 is a schematic plan view illustrating collapse of the embolicprotection device of FIG. 162;

FIGS. 169A to 169C are perspective views illustrating collapse of theembolic protection device of FIG. 162;

FIG. 170 is a perspective view of another filter support and the innertube of FIG. 164;

FIGS. 171 to 173 are plan, side and perspective views respectively of afurther filter support;

FIGS. 174 and 175 are side and perspective views respectively of anotherfilter support;

FIGS. 176 to 178 are plan, side and perspective views of a furtherfilter support;

FIG. 179 is a perspective view of another embolic protection deviceaccording to the invention;

FIG. 180 is a schematic view of another filter support;

FIG. 181 is a development view of the filter support of FIG. 180;

FIG. 182 is an enlarged view of part of the filter support of FIG. 181;

FIG. 183 is a perspective view of another filter support and inner tube;and

FIG. 184 is a perspective view of the filter support of FIG. 183.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, there are illustrated several embolicprotection devices according to the invention. In general the embolicprotection devices comprise a collapsible filter element for deliverythrough a vascular system of a patient. The filter element comprises acollapsible filter body 102 and a filter support 103 for the filter body102, and a carrier which may comprise a tubular member 108 to which thefilter support 103 may be mounted.

The filter body 102 has an inlet end 104 and an outlet end 105. Theinlet end 104 has one or more large inlet openings 106 which are sizedto allow blood and embolic material enter the filter body 102. Theoutlet end 104 has a plurality of small outlet openings 107 which aresize to allow through passage of blood but to retain undesired embolicmaterial within the filter body 102. In this way, the filter elementcaptures and safely retains any undesired embolic material in the bloodstream within the filter body 102 while facilitating continued flow ofblood through the vascular system. Emboli are thus prevented fromflowing further downstream through the vascular system, which couldotherwise have potentially catastrophic results.

The filter body 102 may be of an oriented polymeric material, asdescribed in WO O1/97714A and US 2002/0042627A, the relevant contents ofwhich are incorporated herein by reference.

The filter support 103 is movable between a low-profile, collapsedposition for movement through the vascular system, and an extendedoutwardly projecting position. In this outwardly projecting position,the filter body 102 is supported in an expanded position by the filtersupport 103, so as to maximize the internal volume of the filter body102 to capture and safely retain as much embolic material as possible.The inner tube 108 has a guidewire lumen 112 there through, throughwhich a guidewire may pass for exchange of the filter element 1 over theguidewire. Alternatively, in all embodiments the carrier may comprise aguidewire.

One embolic protection device 100 according to the invention isillustrated in FIGS. 1 to 9. A proximal end of the filter support 103may be fixed to the inner tube 108. Upon collapse of the filter element,the proximal end of the filter support 103 may remain fixed relative tothe inner tube 8, and the filter support 103 collapses distally againstthe inner tube 108. In this collapsed position, the filter support 103is axially elongated relative to the expanded position.

The filter support 103 in this case comprises two round wires 116 whichextend from the proximal end 109. The wires 116 extend together axiallyand radially outwardly in a leg 118 from the proximal end 109, where thewires 116 are fixed to the inner tube 108. The junction of the leg 118with the support hoop is referred to in this specification as theproximal termination point 119.

At a proximal termination point 119, the wires 116 separate, and extendcircumferentially around to form support hoops.

This arrangement of the circumferential hoop formed by the wires 116ensures that in the expanded position, the filter body 102 will besupported by the support frame 103 in circumferential apposition withthe interior wall of the vasculature.

The length of each wire 116 around the hoop is equal. At the proximaltermination point 19, the wires 116 are fixed to each other, and extendgenerally axially and parallel in a bi-filar arrangement.

As the filter support 103 collapses down against the inner tube 108, thewires 116 become torqued. This torqueing action is similar to theprocess of elongation of a coiled spring. Because the support frame 103is defined by round wires 116, the torque developed in each wire 116will be evenly distributed along the length of each wire 116. Inaddition, the bi-filar connection of the wires 116 to each other at thetermination point 19, further assists in torque distribution along thewires 116. Thus, collapse of the filter support 103 does not inducehigh, localized stresses in the filter support 103. In this way, thefilter support 103 may be constructed of wires 116 of a smallcross-sectional area which will collapse down to a very low profile.Furthermore, the collapsed filter element with small wires 116 hasgreater flexibility for ease of advancement of the filter element 1through the vascular system.

The wires 116 are preferably of a self-expanding material, such asNitinol™.

The wires 116 may have a strain distributing linkage element. In thiscase, the linkage element comprises a loop 120 in each wire. The loop120 in this case extends axially and distally of the wire hoop. The loop120 is of generally omega shape as illustrated and is formed integrallyin a wire 116. The loop 120 acts as a strain reliever or distributorwhen the wires 116 are wrapped down as illustrated in FIGS. 6, 7 and 8B.The loop 120 has a relatively large radius resulting in highly efficientstrain distribution. Radii R1, R2, R3 are provided at key points in thesupport frame to relieve strain as illustrated in FIG. 9. In addition,the loop 120 allows the support frame to accommodate varying vesselcontours and sizes. In effect the loop 120 acts as a diameter orcircumference adjuster allowing an embolic protection device to adapt todifference vessel contours and sizes whilst maintaining apposition withthe vessel wall. The strain relieving geometry of the loops enhances thecompliance of the bend points without creating a weakened hinge point,thus ensuring that there is no discontinuity in the circumferential sealagainst the vessel wall.

The loops 120 can also be regarded as distal termination points whichhave a pair of arms which extend axially and generally parallel. Thelooped terminations 120 enhance the ability of the filter support 103 tobe wrapped down to a low profile.

In addition, the looped configuration of the distal termination 120spreads the force exerted by the filter support 103 on the filter body102 over a greater area. In this way, the local pressures applied by thefilter support 103 on the filter body 102 and the walls of a vasculatureare more evenly distributed, this minimizing the possibility of vesseltrauma.

Another important advantage of the strain distributing features such asloops 120 is that they provide an anchor to which connecting elementssuch as tethers may be readily attached as described in more detailbelow.

In use, the filter element is collapsed down and loaded into a deliverycatheter with an associated torqueing of the wires 116 around the hoop.The filter element is then delivered through a vasculature fixed to orover a guidewire using the delivery catheter until the filter element islocated at a desired site in the vasculature.

By moving the delivery catheter proximally relative to the filterelement 1, the element is deployed out of the delivery catheter at thedesired site in the vasculature. The filter support 103 expands radiallyoutwardly to support the filter body 102 in circumferential appositionwith the interior wall of the vasculature. In the fully expandedposition, the wires 116 of the support frame 103 are substantially freeof torque.

The site of deployment of the filter element in the vasculature istypically downstream of a treatment site, such as a region of stenosisin the vasculature. During the performance of a treatment procedure, thefilter element captures and safely retains any embolic material in theblood stream within the filter body 102.

The delivery, deployment and retrieval of the embolic protection deviceof the invention, as described above, is similar to the described in ourW099/23976, WO 01/80776A (US 2002-0052626A) and WO 01/80773A (US2002-0049467A), the relevant contents of which are incorporated hereinby reference. The filter element may be slidably exchanged over theguidewire without any attachment means between the filter element andthe guidewire. A distal stop on the guidewire assists in retrieval ofthe filter element. The guidewire may remain in the vasculature afterretrieval of the filter element.

The support comprises a segmented ring structure which may have twocircumferential wire segments. The wire segments may be connected by astrain distributing linkage element at one end and by a bifilar joint atthe other end. The bifilar joint may be coupled to the carrier by asingle or multiple struts and/or tethers. In one case the strut isattached to the carrier. The connection may permit rotation relative tothe carrier either longitudinally distal or proximal to the point ofattachment to the segmented ring.

In some cases the attachment to the carrier is rigid, in other cases aflexible joint is provided using a tether, a loop, a thinned wiresection or the like. A focal tether may be utilized. A focal tetherimplies that the strut has tensile and compressive integrity but thejoint is not rigid. The joint can thus flex in all directions but itcannot translate.

Individual wires may taper towards the proximal or distal end.

The support frames may have distal, proximal and/or intermediateanchors. One anchor may be fixed and another translatable and/orrotatable relative to the carrier. For example a proximal anchor may betranslatable or in arrangements in which both proximal and distalanchors are provided both may be translatable.

The support frame may comprise a segmented ring or hoop which may havean elliptical cross-section in the free expanded state. The support ringmay be angulated relative to the axis of the inner member.

Various strain distributing linkage elements are illustrated in FIGS. 10to 20. In FIG. 10 the strain distribution is provided by a zig zaglinkage element 103. The omega shape of the preferred loop 120 will beapparent in FIG. 11 however the loop may approximate to a curved V shape131 as illustrated in FIG. 12. Various arrangements in which a straindistributing element is provided by a separate component defining a loop135 are illustrated in FIGS. 13 to 19. The loops 135 may be attached orformed in a number of ways, as illustrated. Another strain distributingdiameter/adjusting feature 136 is illustrated in FIG. 20.

Referring to FIGS. 21 and 22, there is illustrated a further filtersupport 140, which is similar to the filter support of FIGS. 1 to 9, andsimilar elements in FIGS. 21 and 22 are assigned the same referencenumerals. In this case the filter support 140 comprises two wires 141which have an elongate cross-section, in this case a rectangularcross-section, along their proximal section 118. The wires 141 arearranged such that the shorter dimension of the rectangle is alignedalong the radial direction of the filter support, as illustrated in FIG.22.

This flattened wire configuration provides for a filter support 140 withenhanced flexibility. This is achieved because the second moment of areaof the wires 118 is reduced in the flattened configuration.

In addition, the flattened wires 141 minimize the influence of thesupport leg 118 on the outward radial force R1 exerted by the supportframe. This results in a filter support 140 which exerts a relativelyconstant outward radial force R1 around the circumference of the filtersupport (FIG. 22).

In FIG. 24, there is illustrated a filter support 145 in which thecross-sectional area of the round wire 141 decreases radially inwardlyalong the support leg 118 from the proximal termination point 119 to theproximal end of the filter support 145. This tapered support leg 118also achieves the enhanced flexibility, and the relatively constantoutward radial force R1 around the circumference of the filter support145, similar to that discussed previously with reference to FIGS. 21 and22.

As illustrated in FIG. 23, the support leg 118 may be provided by onlyone of the two round wires 116, with the other round wire 116terminating at the proximal termination point 119 where the wires 16 arefixed together. Another arrangement of this type is illustrated in FIG.25.

The configuration of a single wire support leg 118 also achieves theenhanced flexibility, and the relatively constant outward radial forceR1 around the circumference of the filter support 340, similar to thatdiscussed previously with reference to FIGS. 21 and 22.

FIGS. 26 to 28 illustrate another filter support 150, which is similarto the filter support described above, and similar elements are assignedthe same reference numerals. In the filter support 150, the round wires116 extend circumferentially around the support frame in an irregular,wave-like pattern. This configuration increases the area of contactbetween the wires 116 and the filter body 102. As illustrated in FIG. 28this increased area of contact assists in more evenly distributing theradial forces R1 from the support wires 116 to the filter body 102 andhence to the vessel wall. In this way, the risk of vessel trauma due tothe forces exerted by the filter support 150 is minimized.

The radial forces exerted by the filter support on the filter body 102and the walls of a vasculature depend on a number of factors, such asthe diameter of the round wires 116, the material chosen for the wire116 and the properties of that material, the number of wires 116 in thefilter support, the angle of inclination a of the support leg 118 (FIG.9), and the radii R1, R2, R3 of the bends in the filter support. Bysuitably varying these factors, the radial force exerted by the filtersupport 301 may be accurately controlled.

Another important influencing factor on the radial force exerted by thefilter support is the fixing of the wires 116 relative to one another atthe proximal termination points 119 and/or at the distal terminationpoints 120. It may be advantageous to securely fix the wires 116relative to one another at the proximal termination point 119 to achievethe required radial force perpendicular to the proximal terminationpoint 119.

One means of fixing the two wires 116 of the filter support relative toone another at the proximal termination point 119 is to clamp the wire116 together using a tubular polymeric sleeve 151, as illustrated inFIG. 29. The sleeve 151 provides a durable means of fixing the wires 116together which will effectively resist peeling of the wires 116 apart,thus resulting in a highly robust filter element.

The sleeve 151 may be partially of a radiopaque material, such asplatinum, or iridium, to provide visualization of the filter elementduring use.

Alternatively the wires 116 may be clamped together by winding a wire152 around the support wires 16, and then bonding or soldering the wire152 in place around the clamped support wires 16, as illustrated in FIG.30. The wire 152 may be radiopaque.

Another suitable means of fixing the two wires 116 together is todirectly solder, weld or bond the tow wires 116 together.

It will be appreciated that a variety of different means may be used toeffectively fix the wires 116 relative to one another at the proximaltermination point 119 and/or at the distal termination point 120.

As illustrated in FIG. 32, the looped termination 120 may be configuredto fold radially inwardly upon collapse of the filter 160, so that thelooped termination 120 will engage emboli 161 which have collected inthe filter body 102. In this manner, the looped terminations 120 willassist in holding the emboli 161 in place within the filter body 2 andin preventing extrusion of the emboli 161 out of the filter body 102during retrieval of the filter 160. Thus the filter 160 will safelyretain the emboli 161 for removal from the vasculature.

Furthermore, as illustrated in FIGS. 31 to 35, the looped termination120 may be folded radially inwardly to engage against the inner tube108. This arrangement provides enhanced radial support for the filterbody 102.

Upon collapse of the filter 162, the looped terminations 120 slide overthe inner tube 108 until the filter support is in the fully collapsed,elongated configuration.

The loops 120 may be attached at 163 to constrain their freedom ofmovement to the axis of the tube 108 (FIG. 35).

Another filter 170, is illustrated in FIG. 36, and similar elements tothose in previous drawing are assigned the same reference numerals. Thefilter support comprises a single round wire 116 which extends axiallyand radially outwardly in a single leg 118 to the proximal terminationpoint 119. The wire 116 extends circumferentially around the supportframe, looping at the distal termination 120.

The filter body 102, has a single, large inlet opening 106 defined atthe inlet end 104. This arrangement further minimizes the possibility ofany embolic material becoming caught or hung-up on any parts of thefilter at the inlet end 104. This arrangement also further reduces theoverall longitudinal length of the filter 170.

In this case the filter body 102 is fixed directly to the filter supportat the inlet end 104 by wrapping two flaps 171 of the filter body 102around the support wires 116 and then fixing the flaps 171 to the filterbody 102 in this wrapped position (FIG. 36).

In the filter element 175 of FIG. 37, the support leg 118 is fixed tothe inner tube 108 at an inner foot section 176. The inner section 176is inverted to extend distally along the inner tube 108. In addition,the filter body 102 is configured to slide distally over the timer tube108 upon collapse by means of a sleeve 177 fixed to the filter body 102at the distal end 105. The sleeve 117 is also inverted to extendproximally along the inner tube 108.

In this way, by inverting the inner section 176 of the leg 118 and thesleeve 177, the overall longitudinal length of the filter support isminimized. This results in less “parking space” in a vasculature beingrequired to deploy the filter.

Furthermore, by extending the inner section 176 of the leg 118.distally, the possibility of embolic material becoming caught or hung-upat the inlet end 104 of the filter element is reduced.

Referring to FIG. 38 another filter 180 which has a more enhancedtransition to the foot 176 is illustrated.

The filter 185 of FIG. 39 has a proximal support leg 118 that extendsdistally to minimize the length and hence the parking space of thefilter. A support foot 176 is again provided for load distribution.

The filter 190 of FIG. 140 has two proximal support legs 191, 192 whichare axially offset.

Referring to FIGS. 41 to 43 another filter 195 has a single proximalsupport arm 196 which terminates in an open collar 197 which is slidablyengagable with the tubular member 108. This arrangement provides a largesingle inlet opening on deployment. The support frame is held in a lip198 of the filter body/membrane 102.

Another filter 200 is illustrated in FIGS. 44 and 45 which has aconstruction similar to that of FIG. 40 but with the support framehaving neither proximal nor distal support arms. The frame designprovides a very short wrapped length for superior trackability. Thestepped filter arms provide a large inlet opening on deployment.

Various alternative support frames are illustrated in FIGS. 46 to 51. Ineach case, the support hoop is of generally elliptical shape.

In the support 205 of FIGS. 46 and 47 the hoop is biased towards anelliptical shape in its unconstrained state. When constrained within avessel the major axis of the ellipse will be compressed, which will tendto expand the minor axis. This action may assist in the evendistribution of radial force to the vessel wall in the case where thesupport frame is inherently more flexible at the loops than at the topof its proximal arms.

In the support 215 of FIGS. 48 and 49 the proximal arms of the supportframe are staggered so that the hoop is inclined at an angle to the axisof the filter in side view.

Thus although the hoop is actually elliptical it appears circular in endview as shown in FIG. 51.

In the support 210 of FIGS. 50 and 51 the loops of the support frame areoffset so that the hoop is inclined at an angle to the axis of thefilter in top view. Thus although the hoop is actually elliptical itappears circular in end view as shown in FIG. 51.

To enhance visualization of the filter the wire segments and/or thelinkage elements may be rendered radiopaque. Referring to FIG. 52 asection 250 is of a different material or has different properties thanthat of the wire or linkage element 251. The section 250 is ductile andradiopaque. In FIG. 53 the section 250 is formed by straight wires 252some or all of which may be radiopaque. In FIG. 54 the section 250 is ofbraided construction, some or all of which may be radiopaque. Aradiopaque coil 260 is provided in FIG. 55. In FIG. 56 a linkage element120 is rendered radiopaque by using a radiopaque braid. The linkageelement 120 may be of different material and/or have a similarradiopacifying arrangement as shown in FIGS. 52 to 55.

Methods of rendering terminations and/or linkage element radiopaque areillustrated in FIGS. 57 to 62. In FIG. 57 a radiopaque band or cup 270may be used. A radiopaque solder 271 may also be used (FIG. 58).Similarly a radiopaque band 275 may be crimped around the heck of a loop120 as illustrated in FIG. 59. A coil 280 of radiopaque material may bewound around the loop 120 as illustrated in FIG. 60 or across the loopas illustrated in FIGS. 61 and 62.

As illustrated in FIG. 63, at least part of the support may be of amultifilament wire construction. In this case seven Nitinol™ wires 300are wound in a spiral around a single radiopaque wire 301, theradiopaque wire 301 being located substantially along the axis ofbending of the support. The support may have the multifilament wireconstruction along the entire length of the support in this instance.

During bending of the support (FIG. 64), for example upon movement ofthe support to the expanded configuration, each wire 300, 301 bendsindependently of the other wires. As a result, the force required tobend the multifilament support is minimized, and thus the filterachieves enhanced trackability during transport through a tortuousvasculature, such as in coronary applications.

Because the Nitinol™ wires 300 are wound in a spiral around theradiopaque wire 301. This configuration acts to decrease the bendingstresses induced in each wire 300, 301 upon bending (FIG. 64).

The radiopaque wire 301 provides visualization for a clinician duringtransport of the filter 1 through a vasculature and deployment of thefilter in the vasculature. Because the radiopaque wire 301 is locatedalong the neutral axis of the support, the forces required toplastically deform the radiopaque wire 301 as the support moves from thecollapsed configuration to the expanded configuration, upon deploymentof the filter 1, are minimized. In this way the dampening effect of theradiopaque material is minimized.

FIG. 65 illustrates portion of a support 310 of another embolicprotection filter according to the invention. In this case, the supportcomprises two radiopaque wires 311 around which are wound in a spiral aplurality of Nitinol™ wires 312.

A support 315 of a further embolic protection filter according to theinvention is illustrated in FIG. 65. The Nitinol™ wires 318 and theradiopaque wire 317 are braided together to form the multifilament wiresupport 35.

Referring to FIGS. 67 and 68 there is illustrated a support 320 ofanother embolic protection filter according to the invention. Thesupport comprises a single radiopaque wire 321 which extendssubstantially longitudinally, and a single Nitinol™ wire 322 which iswrapped around the radiopaque wire 321 in a coil. As illustrated in FIG.68, the bending stress induced in the Nitinol™ wire 322 upon bending issubstantially less than the bending stresses induced in a solid wirebent through the same angle.

A portion of a wire support 330 of another embolic protection filter isillustrated in FIG. 69. In this case, a single Nitinol™ wire 331 extendssubstantially longitudinally, and a single radiopaque wire 332 iswrapped around the Nitinol™ wire 331 in a coil.

FIG. 70 illustrated part of a support 340 of another embolic protectionfilter according to the invention. The support 340 does not have anyradiopaque wire filaments, instead radiopacity is achieved by aradiopaque core 341 embedded within at least one of the wires 342. Theradiopaque core 341 is located substantially along the neutral axis ofthe Nitinol™ wire 342, and thus the force required to plastically deformthe radiopaque core during movement of the support from the collapsedconfiguration to the expanded configuration is minimized, and thedampening effect of the radiopaque material is minimized.

Referring to FIGS. 71 to 72 a linking element loop 120 may be providedwith radiopacity in a similar manner.

Referring to FIG. 73 or 74 a radiopaque material 345 may be sandwichedbetween two outer layers. Such a frame could be constructed by lasermachining an entire frame (or portion thereof) from a large diameterbi-metal or tri-metal tube. The frame cross section could thus be squareor rectangular as shown in FIG. 73, or could be electropolished tocreate an elliptical or round wire shape as shown in FIG. 74.

The support wire(s) may be of any suitable superelastic material, oralternatively of a high strength material, such as stainless steel.

Referring to FIG. 75, there is illustrated portion of a support 350 ofanother embolic protection filter according to the invention. In thiscase, the support 350 comprises a jacket 351 of a polymeric materialaround multifilament wires 352, 353. The Nitinol™ wires 352 and theradiopaque wire 353 are embedded within the polymeric jacket 351. Avariety of manufacturing procedures, such as ovenmoulding,heat-shrinking, dipping, spraying, painting, depositing may be used tofabricate the wires embedded within the jacket 351. The jacket 351 actsto maintain the structure of the multifilament wire construction intact,and ensures that the wires move in a coordinated manner.

FIG. 76 illustrates a support 360 of another embolic protection filterwhich comprises five Nitinol™ wires 361 wound together in a spiralwithout any radiopaque wire filaments. A radiopaque material, such astungsten, bismuth subcarbonate, barium sulphate, may be loaded into thepolymeric jacket 362 to achieve visualization.

It will be appreciated that a jacket may be used with any of supportstructure described previously. For example, FIG. 77 illustrated asupport 370 of a further embolic protection filter in which the Nitinol™wires 371 and the radiopaque wire 372 are braided together and embeddedin the polymeric jacket 373.

Various ways of rendering a wire, linkage element or tubular member ofthe embolic protection devices of the invention radiopaque areillustrated in FIGS. 78 to 83. In general a radiopaque material 390 isprovided around the element or may itself define the element such as inthe case of the tubular member of FIG. 83.

Referring to FIG. 84 a portion of a support 400 may be in the form ofone or more wires 401 of superelastic material, such as Nitinol™. A coreof radiopaque material is embedded within at least portion of at leastone of the support wires 401. In this case, the core is also in the formof a wire 402 of a suitable radiopaque material, such as gold, orplatinum, or mercury and extends along the length of a support wire. Theradiopaque wire 402 is located substantially along the neutral axis ofbending of the support wire 401. The radiopaque wire 402 providesvisualization for a clinician during transport of the filter through avasculature and deployment of the filter in the vasculature. Byproviding the radiopaque wire 402 as the core of the support wire 401,this minimizes the diameter of the radiopaque wire 402 and its distancefrom the neutral axis. Because the second moment of area of theradiopaque wire 402 is proportional to the fourth power of its diameter,the second moment of area of the radiopaque wire 402 is also minimized.Correspondingly, the forces required to plastically deform theradiopaque wire 402 as the support wire 401 moves from the collapsedconfiguration to the expanded configuration. upon deployment of thefilter, are also minimized. In this manner, the radiopaque coreconfiguration of the invention acts to minimize the dampening effect ofthe radiopaque material, which is necessary to achieve visualization ofthe filter.

The radiopaque material may also be provided in powder form 405, asillustrated in FIG. 85, or in liquid form 406, as illustrated in FIG.86. Because the radiopaque core 405, 406 is embedded within the supportwire 401, the radiopaque powder or radiopaque liquid 26 will be safelyretained and controlled within the support wire 401.

By using a powder or liquid for the radiopaque material, the yieldstress of the radiopaque material is reduced. Thus the forces requiredto move the support wire 401 from the collapsed configuration to theexpanded configuration are further reduced.

The support may comprise a reservoir for enclosing a fluid, thereservoir being provided, which extends circumferentially around thefilter at the inlet end 104 to form an enclosed loop around the inletopening.

The tube may enclose a fluid such as mercury. The temperature of thefluid increases towards body temperature upon deployment of the filterin a vasculature, which causes the fluid to expand. This expansion ofthe fluid forces the support tube towards the expanded configurationuntil the support tube is fully expanded and the filter is supported inthe expanded configuration.

It will be appreciated that the expansible fluid may be of any suitablematerial. By using a radiopaque material, such as mercury, this providesthe additional advantage that visualization of the filter will bepossible during transport of the filter through a vasculature anddeployment of the filter in a vasculature.

In another embolic protection filter according to the invention, thefluid enclosed in the reservoir may be pressurized. In this case, uponrelease of a constraint on the filter, such as upon deployment of thefilter out of the pod of the delivery catheter, the pressurized fluid inthe support reservoir forces the support towards the expandedconfiguration until the filter is supported in the fully expandedconfiguration.

It will be appreciated that the radiopaque core aspect of the invention,and/or the temperature expansible fluid aspect of the invention, and/orthe pressurized fluid aspect of the invention may be used in anysuitable manner or combination with any appropriate medical device.

It will further be appreciated that aspects of the invention may beapplied with any medical device for transport through a body passagewayand deployment in a body.

Referring to FIGS. 87 to 105 there are illustrated various alternativesupport frames incorporating tethering features for connecting thesupport frame distally and/or proximally and/or intermediately to acarrier. Tethers may also be used additionally or alternatively forconnecting various elements of a support frame.

In all cases the tethers may be of any suitable material such as finegauge wire, for example Nitinol™ wire, fiber or polymers. The tethersmay be of solid or braided construction, for example.

Referring to FIGS. 87 to 89 two distal tethers 500, 501 are used toconnect a support hoop 503 to a tubular member 504. The distal tethersprovide added safety and stability to the frame without any increase inthe length of the device when wrapped down as illustrated in FIG. 89.

FIG. 90 illustrates an alternative arrangement of distal tethers 505.

The tethers may be connected to the support frame and carrier in anysuitable fashion. For example, the distal tethers may be double strandedand looped around the support frame as shown in FIG. 87.

Referring to FIGS. 91 to 96 there are illustrated various constructionswith proximal tethers, with FIG. 90 illustrating a basic construction oftwo tethers 520 and a simple hoop support frame.

FIG. 92 illustrates a similar frame to that shown in FIG. 9 previously,but with the proximal frame arms replaced with tethers 520. Additionalstrain relieving loops are provided at the tether connection points toassist in the wrap down of the device as discussed previously inrelation to the distal loops. The use of flexible tethers in place ofwire arms enables the length and stiffness of the wrapped down frame tobe reduced, enhancing the trackability of the device. The flexibility ofthe tethers also enables an even radial force to be provided around thecircumference of the frame without interference from the proximal arms.

In FIG. 97 there are proximal tethers 530 and distal tethers 531. Thisconstruction provides the benefits described in relation to FIG. 92 withthe added benefit of the safety and stability provided by the distaltethers. Again the tethers provide a means of anchoring the supportframe to the carrier without affecting the stiffness or profile of thewrapped device.

In FIG. 98 an offset loop support 540 has a distal tether 541 to preventthe support frame from moving too far proximally and outside the filterbody.

In FIG. 99 another offset loop 550 has a proximal tether 551 to restrainthe movement of the loop section of the frame and thus reduce theoverall length of the wrapped device.

Referring now to FIGS. 100A to 100D there is illustrated one type ofknot 600 in a tether 605 being tied to a linkage element loop 601 of asupport hoop 602.

Referring to FIG. 101 there is illustrated a support frame withcircumferentially extending tethers 610 which allows the frame to movecircumferentially to accommodate a broad vessel size range. The tethers610 also assist in providing added support to a filter body, especiallyin large vessels. There is also an axially extending tether 615interconnecting elements of the support frame.

Referring to FIG. 102, there is illustrated a filter support 620comprising a hollow tube 605 which extends circumferentially around thesupport frame to define a hoop. A tether 626 is looped through the tube605, passing out of the tube 605 at the proximal termination point 119.The tether 626 extends proximally and radially inwardly from theproximal termination point 119 to the inner tube 108 to which the ends627 of the wire 626 are fixed. The tether 626 could be of wire and/or ofa radiopaque material.

Torqueing of the tether 626 within the tube 605 is possible duringcollapsing and expanding of the filter. In the filter support, the tube605 exerts the outward radial force to support the filter body 102 inthe extended outwardly projecting position, and the element 626 acts asa flexible tether to maintain safe, reliable control over the supporttube 605.

The support tube 605 may be of any suitable material, such as polyamideor a superelastic material, for example Nitinol™. The tube 605 may beflexible or rigid. The tube 605 strengthens the proximal terminationpoint 119 while permitting a degree of flexibility at the proximaltermination point 119.

One end of the tether 626 may terminate at the proximal terminationpoint 119 where the end is attached to the other side of the loopedtether 626, with the other end of the tether 626 fixed to the inner tube605.

The invention incorporates circumferential wire angulation into supportstructure design to give maximum circumferential support to the filtermembrane.

Referring now to FIG. 103 a filter 650 with a proximal tether 651extending from the support hoop is illustrated. Other details of thisfilter are as described with reference of FIGS. 36 and 41.

Referring to FIG. 104 there is illustrated an alternative support framein which axially adjacent frame elements 660 are interconnected bytethers 661 which provide additional support for the filter body. Thetethers 661 may be of light gauge thread or wire to facilitate ease ofwrapping down.

Referring to FIG. 105 there is illustrated another filter support framecomprising two axially spaced-apart support hoops 670 interconnected byaxially extending tethers 671. The tethers 671 provide membrane supportbut are of light and flexible material which will add very little to thewrapped profile or stiffness of the support frame. Referring next toFIG. 106, there is illustrated another filter element 700. In this case,the filter support comprises four round wires 116 which extend axiallyand radially outwardly in two legs 118 from the proximal end to twoopposed proximal termination points 119.

The wires 116 separate at the proximal termination points 119 and extendcircumferentially around the support frame 115 until two opposed distaltermination points 120 are reached. The wires 116 then regroup into legs121 at the distal termination points 120. the legs 121 extending axiallyand radially inwardly to the sleeve 111 to which the wires 116 arefixed.

In this case, the proximal termination points 119 are 90° offset fromthe distal termination points 120.

FIG. 107 illustrates a support frame 710 of simpler construction thatthan of FIG. 106.

FIGS. 108 and 109 illustrate the wrapping down of the support frame ofthe filter of FIG. 106.

FIGS. 110 and 111 illustrate another support frame 720 in which thesleeve 111 is located proximally resulting in a shorter wrapped downconfiguration.

FIGS. 112 to 115 illustrate various terminations for the wires in thewire frames of the invention which could be employed to connect a singleproximal or distal frame arm to the circumferential hoop portion of theframe. A construction such as that shown in FIG. 114 allows rotation ofthe hoop relative to the arm, reducing the stresses induced duringwrapping.

Referring to FIG. 116 there is illustrated another support framecomprising a single hoop 800 with two strain distributing loops 801. Oneof the loops 801 has an arm or tether 802 connecting the hoop 800 to atubular member 803. This arrangement provides a support frame with avery short parking space in use. Thus, it can be deployed even if only ashort segment of vessel is available downstream of a treatment location.The support can wrap down in either direction for loading and/orretrieval.

It will be appreciated that the wires 116 may be slidably mounted to theinner tube 108 at both the proximal support leg 118 and the distalsupport leg 121.

It will be further appreciated that by increasing the number of wires116 which define the complete looped cell 117 of the support frame 115,the elongation of the overall filter support, when collapsed down, willbe reduced. For example, the filter support of FIG. 117 comprises eightround wires 116 which extend axially and radially outwardly in four legs118. In this manner, the space required in a vasculature to deploy andretrieve the embolic protection device is correspondingly reduced.

Depending on the configuration of the filter element, the inner tube mayor may not be present. In this case the filter support may be mounteddirectly onto a guidewire for exchange of the filter element over theguidewire.

It will also be appreciated that the shape of one wire 116 of a cell 117does not have to be symmetrical or similar to the shape of the otherwire 116 of the cell 117, provided that the length of each wire 116 isequal.

Furthermore it will be appreciated that a single wire 116, bent back onitself, may be used to define the support frame, in which case the cells117 of the support frame are defined by elements of the single wire, asillustrated in FIG. 118.

FIGS. 119 to 121 illustrate possible means by which the single wire 116may be bent back on itself and wrapped around the inner tube 108. Thissingle wire arrangement enables case of attachment to the inner tube 108without stress concentration points occurring at the regions of loopingof the wire 116 around the inner tube 108.

The fixing of two separate wires 116 to each other in a bi-filararrangement is illustrated in FIG. 122. The fixing means may be providedby, for example, welding, brazing, soldering, or an adhesive joint atthe point of fixation 820. In the case of a single wire 116 bent back onitself to define the support frame, a 180° U-bend at the end of the wire116 may be formed in multiple strain-temperature stages to preventplastic deformation of the wire 116 (FIG. 123). A strain relief means821, such as solder, braze or adhesive, may be provided at the base ofthe U-bend, as illustrated in FIG. 124. Alternatively, a strain relieftube 822 may be provided at the end of the single wire 116 (FIG. 125).

Referring to FIGS. 126 to 129 there is illustrated another embolicprotection filter 830. The wires 116 of the filter support 830 areconnected to the inner tube 108 by two legs 121, in this case, which arefixed directly to the inner tube 108. The four round wires 116 of thefilter support extend axially proximally and radially outwardly in thetwo legs 121 to the two opposed distal termination points 120. The wires116 then separate and extend circumferentially around the support frameuntil the two opposed proximal termination points 119 are reached. Uponcollapse of the filter element, the support frame flips distally overthe legs 121 until the filter support is fully collapsed against theinner tube 108 with the legs 121 at the proximal end of the filtersupport.

By locating the support legs 121 distally of the inlet end 104 of thefilter body 102, this arrangement minimizes the possibility of embolicmaterial becoming caught or hung-up at the inlet openings 106. In thismanner, substantially all of the embolic material is retained safelywith the filter body 102 for subsequent retrieval from the vascularsystem using a retrieval catheter 832 as illustrated in FIGS. 128 and129.

As illustrated with the filter 840 of FIGS. 130 and 131, a proximal neck841 of the filter body may be inverted to extend distally rather thanproximally, as is the case with the filter element of FIG. 129. Thisarrangement reduces the overall longitudinal length of the filterelement, and thus the filter element may be deployed and retrieved witha shorter “parking space” in the vasculature.

FIGS. 132 to 134 illustrate the process of inverting the proximal neck841. The neck 841 is split along each side 842 (FIG. 133), and the neck841 is then pushed distally into the interior of the filter body (FIG.134).

In addition, the longitudinal length of the filter element of FIG. 130is further shortened by providing a hemi-spherically shaped proximalnose 845 instead of a conical nose, as is the case with the filterelement of FIG. 129. Furthermore, the overall crossing profile of thefilter element is reduced by means of the hemi-spherical nose 845.

Referring to FIG. 135 there is illustrated a filter with a proximallyextending neck 847 which is split into two parts 847.

Referring to FIGS. 136 and 137 there is illustrated a filter 870 inwhich the filter body is connected directly to the frame by means offolded filter seams.

FIG. 137 shows a variant filter 875 in which a second frame providesadditional body support to the filter.

Referring to FIG. 138, there is illustrated another filter element 880,with a filter body which, in this case, has a single, large inletopening 881 defined at the inlet end 104. This arrangement furtherminimizes the possibility of any embolic material becoming caught orhung-up on any parts of the filter element at the inlet end 104. Thisarrangement also further reduces the overall longitudinal length of thefilter element.

FIGS. 139 and 140 illustrate a further filter element 885, in which theproximal end 9 of the filter support is fixed to the inner tube 108,while the distal end 110 of the filler support remains unconnected tothe inner tube 108. The filter support comprises four round wires 116which extend axially and radially outwardly in two legs 118 from theproximal end 109 to the proximal termination points 119. At the proximaltermination points 119, the wires 116 separate and extendcircumferentially around the support frame until the two distaltermination points 120 are reached. The proximal termination points 119are circumferentially offset by 90° from the distal termination points120.

The proximal end 109 of the filter support 103 is fixed to the innertube 108, and the distal end 110 of the filter support 103 is fixed to asleeve 111 which is slidable over the inner tube 108. Upon collapse ofthe filter element, the proximal end 109 of the filter support 103remains fixed relative to the inner tube 108, and the distal sleeve 111slides over the tube 108, until the filter support 103 is fullycollapsed against the inner tube 108. In this collapsed position, thefilter support 103 is axially elongated relative to the expandedposition.

The filter support 103 is illustrated in FIG. 142. The filter support103 comprises two round wires 116 which extend from the proximal end 109to the distal end 110. The wires 116 extend together axially andradially outwardly in a leg 118 from the proximal end 109, where thewires 116 are fixed to the inner tube 108, to a central support hoop115. The junction of the leg 118 with the support hoop 115 is referredto in this specification as the proximal termination point 119.

At the proximal termination point 119, the wires 116 separate, andextend circumferentially around the support hoop 115 until a symmetricaldistal termination point 120 is reached. In this way, the two wires 116define the support hoop 115.

At the distal termination point 120, the wires 116 regroup into a leg121 which extends axially, and then axially and radially inwardly to thesleeve 111 to which the wires 116 are fixed.

The path of the two wires 116 around the support hoop 115 togetherdefine a cell 116 which forms a complete loop, as illustrated in FIG.142. This arrangement of the circumferential looped cell 117 ensuresthat in the expanded position, the filter body 102 will be supported bythe support hoop 115 in circumferential apposition with the interiorwall of the vasculature.

The length of each wire 116 around the cell 117 is equal. At theproximal and distal termination points 119, 120, the wires 116 are fixedto each other, and extend generally axially and parallel in a bi-filararrangement.

As the filter support 103 collapses down against the inner tube 108, thewires 116 around the cell 117 become torqued. This torqueing action issimilar to the process of elongation of a coiled spring.

Because the support frame 115 is defined by round wires 116, the torquedeveloped in each wire 116 will be evenly distributed along the lengthof each wire 116. In addition, the bi-filar connection of the wires 116to each other at the termination points 119, 120 further assists intorque distribution along the wires 116.

Thus, collapse of the filter support 103 does not induce high, localizedstresses in the filter support 103. In this way, the filter support 103may be constructed of wires 116 of a small cross-sectional area whichwill collapse down to a very low profile.

Furthermore the collapsed filter element with small wires 116 hasgreater flexibility for ease of advancement of the filter elementthrough the vascular system.

As illustrated in FIG. 142, the proximal termination point 119 iscircumferentially offset by 180° from the distal termination point 120.

The wires 116 are preferably of a self-expanding material, such asNitinol™, and the inner tube 108 is preferably of gold. This arrangementprovides for radiopacity.

In use, the filter element is collapsed down and loaded into a deliverycatheter with an associated torqueing of the wires 116 around the cell117. The filter element is then delivered through a vasculature fixed toor over a guidewire using the delivery catheter until the filter elementis located at a desired site in the vasculature.

By moving the delivery catheter proximally relative to the filterelement, the filter element is deployed out of the delivery catheter atthe desired site in the vasculature. The filter support 103 expandsradially outwardly to support the filter body 102 in circumferentialapposition with the interior wall of the vasculature. In the fullyexpanded position, the wires 116 of the support frame 115 aresubstantially free of torque.

The site of deployment of the filter element in the vasculature istypically downstream of a treatment site, such as a region of stenosisin the vasculature. During the performance of a treatment procedure, thefilter element captures and safely retains any embolic material in theblood stream within the filter body 102.

After completion of the treatment procedure, the filter element iscollapsed down and retrieved into a retrieval catheter with any retainedembolic material within the filter body 102. The wires 116 around thesupport frame 115 are again torqued during collapse.

The retrieval catheter is then withdrawn from the vasculature with thefilter element within the retrieval catheter.

Referring to FIGS. 142A and 142B there is illustrated a lower portionand a top view of a modified support frame similar to FIG. 142 in whichthe loops defined by the wires 115 are offset at point 120. This offsetcould also be applied to point 119. Such a design may be of benefit inbroadening the area of circumferential apposition and sealing providedby the filter.

Referring to FIG. 143 there is illustrated a support frame. 910 similarto that of FIG. 142 except that in this case the distal and proximallegs 121, 118 are defined by a single wire, the second wire extendingonly a short distance distally or proximally from the distal andproximal termination points respectively.

Referring to FIG. 144 there is illustrated another embolic protectionfilter 920 which comprises a single hoop support frame 921 withadditional wire support anus 922, 923. In this case the distal supportleg is connected to the proximal end of the carrier. Thus additionalsupport is provided to the hoop without any impact on the wrapped lengthof the device.

Referring to FIG. 145 there is illustrated a further embolic protectionfilter 930 comprising support hoops 931, 932 which are offset.

Referring to FIGS. 146 to 148 there are illustrated various filterframes comprising a wire support hoops which may have straindistribution features and/or tethers as described above.

The frame 935 of FIG. 146 comprises a single wire offset hoop 936. Theframe 938 of FIG. 147 is preferred because parking space is minimizedwhile facilitating wrapdown. It will be noted the support comprises anoffset wire support hoop 939 with an axially extending proximallyextending wire section 940 and an inwardly extending support arm 941.The frame 945 of FIG. 148 is similar to that of FIG. 147 except thatthere are two oppositely directed offset hoops 946, 947 similar to theframe used in the filter of FIG. 145.

Another support frame 950 is illustrated in FIGS. 149 to 150 which isagain of wire and includes strain distributing loop features 951 whichmay be of any suitable type as described above and exemplified in FIGS.150 and 151.

The support frame 960 of FIGS. 152 and 153 again has an offset hoop 961which can wrap down as illustrated in FIG. 153.

Referring to FIGS. 154 and 155, there is illustrated another filterelement 970, in which the filter support 972 comprises four round wires116. At the proximal termination point 119, two of the wires 116 extendcircumferentially around the support frame 115 to define a first call117, and the other two wires 116 extend axially and then extendcircumferentially around the support frame to define a second cell 1117.

In this manner, the wires 116 define two axially spaced-apart cells 117,each cell 117 forming a complete loop, as illustrated in FIG. 155. Thisarrangement ensures that in the expanded position, the filter body 102will be supported by the support frame in tubular apposition with theinterior wall of the vasculature. The tubular apposition furtherminimizes the possibility of any flow path for blood occurring betweenthe filter body 102 and the vasculature wall to bypass the filterelement. At the distal termination point 120, all four wires 116 regroupinto leg 121.

It will be appreciated that as the wires 116 extend circumferentiallyaround the support frame 115, the wires 116 may also extend partiallyaxially, so that the defined cell 117 partially slopes axially.Furthermore, the wires 116 may be at least partially of an arcuateshape, as illustrated in the support frame 973 of FIG. 156. In eithercase, the sloping or arcuate configuration of the wires 116 increasesthe contact area between the wires 116 and the filter body 102, and inthis way, the supporting force exerted by the wires 116 on the filterbody 102 is more evenly distributed. This arrangement minimizes anytrauma experienced by the vasculature due to the apposition of thefilter element with the vasculature.

FIG. 157 illustrates another filter support 975, which is similar to thefilter support of FIGS. 154 and 155, and similar elements in FIG. 157are assigned the same reference numerals. In this case, the filtersupport comprises six round wires 116. The wires 116 extend axially andradially outwardly in two legs 118 from the proximal end 109 to twoopposed proximal termination points 119. As illustrated in FIG. 157, thewires 116 are arranged to define two axially spaced-apart, complete loopcells 117. In addition, two of the wires 116 act as axial bridges toconnect the two cells 117. At the distal termination points 120, thewires 116 regroup into two legs 121. The proximal termination points 119are circumferentially aligned with the distal termination points 120, inthis case.

The support frame 980 of FIG. 158 is similar to that of FIG. 157 exceptthat in this case there are no proximal support arms with consequentialreduced filter length.

Referring to FIGS. 159 to 161, there is illustrated another filtersupport 990, which is similar to the filter support of FIGS. 154 and155, and similar elements are assigned the same reference numerals. Inthis case, the filter support 990 comprises only two round wires 116.The wires 116 extend together axially and radially outwardly in a singleleg 118 from the proximal end 109 to the proximal termination point 119.The wires 116 then separate and extend circumferentially around thesupport frame 115 to define the first cell 117. The wires 116 extendaxially, and then circumferentially around the support frame 115 todefine the second cell 117. At the distal termination point 120, thewires 116 regroup into a single leg 121.

As illustrated in FIG. 161, the proximal termination point 119 iscircumferentially aligned with the distal termination point 120.

Referring to the drawings, and initially to FIGS. 162 to 169 thereof,there is illustrated an embolic protection device according to theinvention. The embolic protection device comprises a collapsible filterelement 1 for delivery through a vascular system of a patient.

The filter element 1 comprises a collapsible filter body 2 and a filtersupport 3 for the filter body 2, and an inner tube 8, around which thefilter support 3 is mounted.

The filter body 2 has an inlet end 4 and an outlet end 5. The inlet end4 has one or more, and in this case two, large inlet openings 6 whichare sized to allow blood and embolic material enter the filter body 2.The outlet end 5 has a plurality of small outlet openings 7 which aresized to allow through passage of blood but to retain undesired embolicmaterial within the filter body 2. In this way, the filter element 1captures and safely retains any undesired embolic material in the bloodstream within the filter body 2 while facilitating continued flow ofblood through the vascular system. Emboli are thus prevented fromflowing further downstream through the vascular system, which couldotherwise have potentially catastrophic results. The filter body 2 maybe of an oriented polymeric material. as described in our WO 01/97714Aand US 2002/0042627A, the relevant contents of which are incorporatedherein by reference.

The filter support 3 is movable between a low profile, collapsedposition (FIG. 169C) for movement through the vascular system, and anextended outwardly projecting position (FIG. 169A). As particularlyillustrated in FIG. 2, in this outwardly projecting position, the filerbody 2 is supported in an expanded position by the filter support 3 soas to maximize the internal volume of the filter body 2 to capture andsafely retain as much embolic material as possible.

The inner tube 8 has a guidewire lumen 12 there through, through which aguidewire may pass for exchange of the filter element 1 over theguidewire.

The proximal end 9 of the filter support 3 is fixed to the inner tube 8,and the distal end 10 of the filter support 3 is fixed to a sleeve 11which is slidable over the inner tube 8, as illustrated in FIG. 164. Asillustrated in FIGS. 167 to 169C, upon collapse of the filter element 1,the proximal end 9 of the filter support 3 remains fixed relative to theinner tube 8, and the distal sleeve 11 slides over the tube 8 (FIG.169B), until the filter support 3 is fully collapsed against the innertube 8 (FIG. 169C). The partially and fully collapsed positions of thefilter support 3 are illustrated by dashed lines in FIGS. 167 and 168.In the fully collapsed position of (FIG. 169C), the filter support 3 isaxially elongated relative to the expanded position.

The filter support 3 is illustrated in detail in FIGS. 164 to 166. Thefilter support 3 comprises eight round wires 16 which extend from theproximal end 9 to the distal end 10. The wires 16 extend axially andradially outwardly in two legs 18 from the proximal end 9, where thewires 16 are fixed to the inner tube 8, to a central tubular supportframe portion 15. The junction points of the legs 18 with the tubularframe 15 are referred to in this specification as the proximaltermination points 19.

At each proximal termination point 19, the wires 16 separate, and thenextend axially along and circumferentially around the tubular frame 15until symmetrical distal termination points 20 are reached. At thesedistal termination points 20, the wires 16 regroup into two legs 21which extend axially and radially inwardly to the sleeve 1, to which thewires 16 are fixed. In this way, the wires 16 define the central tubularframe portion 15.

The path of the wires 16 around and along the tubular frame portion 15defines four cells 17, with each cell 17 forming a segment of thetubular frame 15 (FIG. 166). Together the four cells 17 extendcircumferentially around the tubular frame 15 in a complete loop.

This arrangement of the tubular frame 15 ensures that in the expandedposition, the filter body 2 will be supported by the tubular frame 15 intubular apposition with the interior wall of the vasculature. Thetubular apposition further minimizes the possibility of any flow pathfor blood occurring between the filter body 2 and the vasculature wallto bypass the filter element 1.

Each cell 17 is defined by two of the wires 16 which are arranged, inthe expanded position. in a generally parallelogram, “hysteresis loop”shape. The length of each wire 16 around the cell 17 is equal. At theproximal and distal termination points 19, 20, adjacent wires 16 arefixed to each other, and extend generally axially and parallel in abi-filar arrangement. Adjacent cells 17 within the tubular frame 15 arealso connected together by fixing a wire 16 in one cell 17 to a wire 16in an adjacent cell 17.

As the filter support 3 collapses down against the inner tube 8, thewires 16 around each cell 17 become torqued. This torqueing action issimilar to the process of elongation of a coiled spring.

Because the tubular support frame 15 is defined by round wires 16, thetorque developed in each wire 16 will be evenly distributed along thelength of each wire 16. In addition, the bi-filar connection of thewires 16 to each other at the termination points 19, 20 further assistsin torque distribution along the wires 16.

Thus, collapse of the filter support 3 does not induce high, localizedstresses in the filter support 3. In this way, the filter support 3 maybe constructed of wires 16 of a small cross-sectional area which willcollapse down to a very low-profile. Furthermore the collapsed filterelement 1 with small wires 16 has greater flexibility for ease ofadvancement of the filter element 1 through the vascular system.

As illustrated in FIGS. 165 and 166, the proximal termination points 19are circumferentially offset by 90° from the distal termination points20.

In use, the filter element 1 is collapsed down and loaded into adelivery catheter with an associated torqueing of the wires 16 aroundthe cells 17. The filter element 1 is then delivered through avasculature fixed to or over a guidewire using the delivery catheteruntil the filter element 1 is located at a desired site in thevasculature.

By moving the delivery catheter proximally relative to the filterelement 1, the filter element 1 is deployed out of the delivery catheterat the desired site in the vasculature. The filter support 3 expandsradially outwardly to support the filter body 2 in tubular appositionwith the interior wall of the vasculature. In the fully expandedposition, the wires 16 of the tubular support frame 15 are substantiallyfree of torque.

The site of deployment of the filter element 1 in the vasculature istypically downstream of a treatment site, such as a region of stenosisin the vasculature. During the performance of a treatment procedure, thefilter element 1 captures and safely retains any embolic material in theblood stream within the filter body 2.

After completion of the treatment procedure, the filter element 1 iscollapsed down and retrieved into a retrieval catheter with any retainedembolic material within the filter body 2. The wires 16 around thetubular wire support frame 15 are again torqued during collapse.

The retrieval catheter is then withdrawn from the vasculature with thefilter element 1 within the retrieval catheter.

The delivery, deployment and retrieval of the embolic protection deviceof the invention, as described above, is similar to that described inour WO 99/23976A; WO 01/80776A (US 2002-0052676A) and WO 01/80773A (US2002-0049467A), the relevant contents of which are incorporated hereinby reference. The filter element 1 may be slidably exchanged over theguidewire without any attachment means between the filter element 1 andthe guidewire. A distal stop on the guidewire assists in retrieval ofthe filter element 1. The guidewire may remain in the vasculature afterretrieval of the filter element 1.

FIG. 170 illustrates another filter support 30, which is similar to thefilter support 3 of FIGS. 162 to 168, and similar elements in FIG. 170are assigned the same reference numerals.

In this case, the filter support 30 comprises only six wires 16, whichdefine only three tubular segment cells 17 as the wires 16 extendaxially along and circumferentially around the tubular frame 15. Thethree cells 17 do not form a complete 360° loop around the tubular frame15. An extension wire 31 is provided, in this case, to provide supportto the filter body 2 between the two circumferentially spaced-apartcells 17. The linkage element 31 may provide a diameter adjustingfeature.

Referring to FIGS. 171 to 173, there is illustrated another filtersupport 35, which is similar to the filter support 3 of FIGS. 162 to169, and similar elements in FIGS. 171 to 173 are assigned the samereference numerals.

The wires 16 extend, in this case, circumferentially around the tubularframe 15 in an “S-shape”. The S-shape increases the contact area betweenthe wires 16 and the filter body 2, and in this way, the supportingforce exerted by the wires 16 on the filter body 2 is more evenlydistributed. This arrangement minimizes any trauma experienced by thevasculature due to the apposition of the filter element 1 with thevasculature.

An alternative filter support 40 having wires 16 with a more exaggeratedS-shaped portion 41 is illustrated in FIGS. 174 and 175.

It will be appreciated that the shape of one wire 16 of a cell 17 doesnot have to be symmetrical or similar to the shape of the other wire 16of the cell 17, provided that the length of each wire 16 is equal.

Referring to FIGS. 176 to 178, there is illustrated another filtersupport 45, which is similar to the filter support 3 of FIGS. 162 to169, and similar elements in FIGS. 176 to 178 are assigned the samereference numerals.

In this case, the filter support 45 comprises only four wires 16, whichextend circumferentially around and axially along the tubular supportframe 15 to define two cells. The two cells have a hexagonal, hysteresisloop shape, and together the two cells 17 extend circumferentiallyaround the tubular frame 15 in a complete loop.

The proximal termination points 19 are circumferentially aligned withthe distal termination points 20.

Another support frame 50, illustrated in FIG. 179, is similar to thesupport frame 3 of FIGS. 161 to 169, and similar elements if FIG. 179are assigned the same reference numerals.

In this case, the wires 16 are fixed to inner tube 8 at a point 51distally of the tubular support frame portion 15. The wires 16 extendfrom the fixation point 51 axially proximally and radially outwardly ina single leg 52 to the tubular support frame portion 15.

By providing a single proximal support leg 52, and by locating this leg52 distally of the inlet end 4 of the filter body 2. this arrangementminimizes the possibility of embolic material becoming caught or hung-upon the leg 18 at the inlet openings 6. In this manner, substantially allof the embolic material is retained safely within the filter body 2 forsubsequent retrieval from the vascular system.

The wires 16 are preferably of a self-expanding material, such asNitinol™, and the inner tube 8 is preferably of gold. This arrangementprovides for radiopacity.

It will be appreciated that a plurality of cells 17 may be defined bythe wires 16 around the tubular support frame 15, as illustrated in FIG.18. Each wire 16 may be fixed to a wire 16 in an adjacent cell 17 (FIG.181) by welding, or by adhesive means 57 (FIG. 182), or by any othersuitable means.

The wires 16 may be slidably mounted to the inner tube 8 at both theproximal support leg 18 and the distal support leg 21.

By increasing the number of wires 16 which define the cells 17 of thetubular support frame 15, the elongation of the overall filter support,when collapsed down, is reduced. In this way, the space required in avasculature to deploy and retrieve the embolic protection device is alsoreduced.

Depending on the configuration of the filter element, the inner tube maynot be present. In this case the filter support will be mounted directlyonto the guidewire for exchange of the filter element over theguidewire.

It will be appreciated that a single wire 16, bent back on itself, maybe used to define the tubular support frame 15, in which case the cells17 of the tubular support frame 15 are defined by elements of the singlewire 16, as illustrated in FIGS. 21 and 22. The support frame 90 ofFIGS. 183 and 184 is similar to the support frame 3 above, with theexception that the support frame is defined by a single wire 16 bentback on itself.

A proximal neck of the filter body may be inverted to extend distallyrather than proximally. This arrangement reduces the overalllongitudinal length of the embolic protection device, and thus theembolic protection device may be deployed and retrieved with a shorter“parking space” in the vasculature. To invert the proximal neck, theneck may be split along each side, and then the pushed distally into theinterior of the filter body.

In addition, the longitudinal length of the embolic protection devicemay be further shortened by providing a hemi-spherically shaped proximalnose instead of a conical nose. Furthermore, the overall crossingprofile of the embolic protection device may be reduced by means of thehemi-spherical nose.

The invention incorporates circumferential wire angulation into supportstructure design to give maximum circumferential support to the filtermembrane.

The angulated hysteresis structure/cell configurations of the inventionare particularly suitable as support structures because the strainenergy is distributed over long lengths of the wire structure. Thewrapping/loading mechanisms of these hysteresis structures are both abending/straightening of the constituent wires as well as atwisting/torsion of the wires. The energy applied/introduced during theloading process is both bending and torsional strain energy. Theseenergies due to their nature and the method by which the supportstructure folds/loads are distributed over long lengths of the wire asopposed to concentrated focal points so that the level of energy withinthe wire at any point does not exceed the elastic strain energy limits.Hysteresis designs optimize the strain distribution along the wirelengths. With these designs there is distributed bending and torsionalstrain along the wires. The component of radial force is converted totorque strain energy. The corollary of this principle. that thetorsional strain energy provides radial stiffness, also applies.

Angulated hysteresis structures also enable large radial forces to beachieved from structures with small wire diameters. The reason for thisis that these designs use a greater proportion of the wires' torsionalstrain resistance. The wires offer far greater resistance to torsionalstrain than to bending strain and therefore these designs optimize thisfeature. The angulated hysteresis structure design arranges the wires sothat the load induces torsional strain and therefore delivers far higherperformance with small wire diameters than those designs that rely onthe bending strain/resistance.

The hysteresis support structure of the invention has sections of wirecurvature that can be defined in 3D planes. These sections of wire havegeometrical properties such as a radius of curvature and a centre ofradius of curvature. As the hysteresis structure designs are loaded anddeployed, the geometrical properties of these sections change that isthe radius of curvature changes and the center for the radius ofcurvature moves in a path that can only be defined within a 3D plane.

Even relatively simple hysteresis designs are made up of numeroussections of curvature with their corresponding radius of curvaturejoined end to end to form a complete hysteresis loop. These sections ofcurvature depending on the complexity of the design may be combinationsof concave and convex elements/segments. The hysteresis loops themselvescan be various shapes and there are multitudes of hysteresis loop/cellgeometries.

A wire or laser cut support structure design based on a hysteresis celltype design typically may have four arms acting to provide uniformradial force to give good vessel apposition In attempting to providesupport over the complete body length structure designs tend to havemultiple arms/cells providing the support. The problems with many ofthese designs is the excessive elongation associated with them duringloading. The advantage with the invention in suit is that it onlyextends the same length whether one/two or multiple arms are used. Theinvention also lends itself to low wrapping profiles, because duringloading it contracts both radially and circumferentially leavingparallel straight wires which often prove to be the easiest for loading.

Further advantages of the round wire arrangements include:

Using a round wire allows for substantially more of the strain energyinduced during loading/wrapping down into a low profile to be stored astorque along the wire lengths. This means that the strain energy is moreevenly distributed within the wires than with conventional sectiondesigns, in which the strain energy generally becomes concentratedaround the bend points which can cause problems such as exceeding theelastic strain energy limit at these locations.

The invention also has the advantage of being more trackable andflexible. This design achieves this by allowing the structure to hingeat points. Planes through these points demonstrate that bending at thesehinge points is very easy.

Furthermore. the radial force may be altered by:

a) changing the wire diameter;

b) changing the proximal and distal cone angles.

Points of stress concentration can become strained plastically andresult in poor support structure performance.

Conventional approaches to dealing with these issues involve designingin strain distributing geometric features to spread these strains over agreater area of the structure. Another approach involves the use ofthinning out sections in the area of high strain. At a given radius ofcurvature the strain in a thin section is less than that of a thicksection. Thinning however compromises the overall support provided bythe structure.

The filter support of the invention provides for torsional strain andthus eliminates the need to use section thinning or thickening todistribute strain.

When collapse strains are evenly distributed, it is possible that theoverall level of strain in the system can be increased without inducingplastic deformation. This makes it possible to achieve a high level ofradial support from small diameter support members.

Designs that induce torque-strain into the support structure duringcollapse are particularly advantageous. Bending strains tend very oftento have a strong cantilever effect with the strain becoming localized atpoints of stress concentration.

The torque strain in the wire can be released in a variety of expansionpathways. This means that the release of the torque is not inhibitedwhen uniaxial resistance is encountered. This feature helps the supportstructure deliver good apposition to eccentric vessels. This is animportant aspect of the invention, especially when the filter is placedin diseased vessel segments.

The geometric configuration of the filter support aligns the wires ofthe cell in a substantially circumferential direction in the expandedstate. This ensures that radial pressure applied by the vessel isinitially transmitted as compressive hoop stress to the structure.

The compressive component of applied stress decreases as the systemcollapses, however the torsional resistance increases resulting in arelatively flatter loading stress curve.

It will be appreciated that the body maybe attached to or independent ofthe support frame.

The invention is not limited to the embodiments hereinbefore describedwhich may be varied in detail.

1. An embolic protection filter comprising: a filter body having aninlet end and an outlet end, the inlet end of the filter body having oneor more inlet openings sized to allow blood and embolic material enterthe filter body, the outlet end of the filter body having a plurality ofoutlet openings sized to allow through passage of blood but to retainundesired embolic material within the filter body; and a filter supportmovable between a collapsed position for movement through the vascularsystem and an extended outwardly projecting position to support thefilter body in the expanded position; the filter support comprising oneor more support arms; in the extended outwardly projecting position, theone or more support arms extending circumferentially in a planesubstantially perpendicular to the longitudinal axis of the filter; andin the collapsed position, the one or more support arms extendinglongitudinally substantially parallel to the longitudinal axis of thefilter.
 2. A filter as claimed in claim 1, wherein the filter supportcomprises a strain distributing linking element connecting a firstsupport arm to an adjacent second support arm.
 3. A filter as claimed inclaim 2, wherein the support arm is pivotably movable relative to thestrain distributing linking element upon movement of the filter supportbetween the collapsed position and the extended outwardly projectingposition.
 4. A filter as claimed in claim 2, wherein the support arm isformed integrally with the strain distributing linking element.
 5. Afilter as claimed in claim 1, wherein the filter support comprises acoupling part for coupling the filter to a guidewire.
 6. A filter asclaimed in claim 5, wherein the coupling part defines a lumentherethrough through which a guidewire is insertable.
 7. A filter asclaimed in claim 5, wherein the coupling part comprises a tube.
 8. Afilter as claimed in claim 5, wherein the filter support comprises atleast one support leg to connect the one or more support arms to thecoupling part.
 9. A filter as claimed in claim 8, wherein the supportleg is formed integrally with the support arm.
 10. A filter as claimedin claim 8, wherein the support leg extends radially inwardly from thesupport arm in the extended outwardly projecting position.
 11. A filteras claimed in claim 8, wherein the support leg extends proximally fromthe support arm in the extended outwardly projecting position.
 12. Afilter as claimed in claim 8, wherein the support leg extendslongitudinally substantially parallel to the longitudinal axis of thefilter in the collapsed position.
 13. A filter as claimed in claim 8,wherein the support leg is pivotably movable relative to the couplingpart upon movement of the filter support between the collapsed positionand the extended outwardly projecting position.
 14. A filter as claimedin claim 8, wherein the support arm is pivotably movable relative to thesupport leg upon movement of the filter support between the collapsedposition and the extended outwardly projecting position.